Gear unit at least partially filled with oil

ABSTRACT

A gear unit at least partially filled with oil, 
     wherein 
     
         
         
           
             a device is provided in the gear unit for lowering the oil level, especially of the oil pan of the gear unit, during operation, the device including at least one temporary storage.

FIELD OF THE INVENTION

The present invention relates to a gear unit at least partially filledwith oil.

BACKGROUND INFORMATION

It is well-known that gear units having oil lubrication are practicable,the oil, i.e., liquid, collecting in the bottom part of the gear-unitinterior when the gear unit is not in operation, thus when the gearwheels are stationary, and forming the oil pan there which has an oillevel that corresponds to the filling level upon pouring in the oil.During operation of the gear unit, especially at nominal speed of theinput shaft and/or output shaft, the gearing parts of the gear unitspray and hurl oil around. In particular, oil is also sprayed out fromthe gearings engaging with each other. The quantities of oil sprayedaround lower the oil level only insignificantly during operation of thegear unit.

SUMMARY

Example embodiments of the present invention provide a gear unit inwhich the intention is for as much power as possible to be transmittableper unit volume.

Among features of example embodiments of the present invention withrespect to the gear unit are that it is a gear unit at least partiallyfilled with oil, a device being provided in the gear unit for loweringthe oil level, especially of the oil pan of the gear unit, duringoperation, the device including at least one temporary storage.

This is advantageous because the oil level is lowered significantly,since oil is filled temporarily into a temporary storage, thus, areceptacle. Therefore, churning losses are reducible, and nevertheless,good lubrication is attainable when starting the gear unit, even thougha protracted standstill may have taken place beforehand.

In example embodiments, the oil level in the temporary storage is higherduring operation of the gear unit than the oil level, especially of theoil pan of the gear unit. This offers the advantage that the temporarystorage is able to be emptied automatically during standstill of thegear unit.

In example embodiments, the temporary storage is located in the interiorof the gear unit. This is advantageous because no furtherhousing-forming part, other than the gear housing, is necessary, and thespatial area of the gear unit may be well-utilized.

In example embodiments, the temporary storage is in the form of areceptacle whose wall is formed at least partially by a sheet-metalpiece \ and/or a plastic piece, especially at least partially togetherwith the inner wall of the housing of the gear unit. This has theadvantage that the temporary storage may be produced inexpensively.

In example embodiments, the oil level of the gear unit, especially theoil pan of the gear unit, is lower during operation lasting for aminimum duration than the oil level during long-term standstill of thegear unit. The advantage in this case is that churning losses arereducible, and therefore more power is attainable per unit volume due tothe substantial lowering of the oil level.

In example embodiments, oil from the oil pan of the gear unit is able tobe delivered to the temporary storage, especially with the aid of adelivery device, in particular, the temporary storage being disposed inthe interior of the gear unit, thus, being surrounded by the gearhousing in housing-forming fashion. This is advantageous because it ispossible to dispense with an additional housing, and the inner spatialarea may be well-used.

In example embodiments, the temporary storage is in the form of areceptacle which has openings of the kind that it is able to be emptiedthrough these openings. This offers the advantage that it is able to beemptied automatically during standstill, and therefore the oil level ofthe oil pan then rises substantially.

In example embodiments, the temporary storage is in the form of areceptacle that has openings such that, and the delivery device isconceived and implemented such that the maximum oil flow delivered bythe delivery device, especially during operation of the gear unit withthe nominal speed of the gear unit, is greater than the oil flowreturned from the temporary storage to the oil pan, effected through theopenings. The advantage is that the temporary storage fills increasinglyduring operation and empties during standstill of the gear unit.

In example embodiments, the oil level, especially of the oil pan of thegear unit, is lower during operation than the oil level during long-termstandstill of the gear unit, in particular, a device being provided forlowering the operational oil level, the device for lowering especiallybeing a device for the temporary storage of oil. The advantage in thiscontext is that when starting the gear unit, the bearings and gearingparts are soaked well by oil, since the oil level is very high at thebeginning. In operation, thus, when the oil level is lower, the churninglosses are reduced, and the bearings or gearing parts are able to belubricated from the temporary storage via other delivery device. Inoperation, these delivery devices are operable without representing anadditional energy loss of the gear unit.

In example embodiments, a temporary storage is provided to which oil isable to be fed from the oil pan of the gear unit, especially with theaid of a delivery device; in particular, the temporary storage isdisposed in the interior of the gear unit, thus, is surrounded by thegear housing in housing-forming fashion. This is advantageous because noadditional housing or an additional spatial area is necessary for thetemporary storage; rather, the spatial area present in the housing ofthe gear unit is usable. This holds true especially for a housing whichsurrounds the gearing parts in essentially cuboidal fashion, a beveledarea placed on the cuboid being able to be provided in the area of theinput shaft. Advantageously, a cube housing is able to be producedeasily and inexpensively, and exhibits great strength accompanied bysmall wall thickness and small amount of material used. Therefore, asubstantially cuboidal interior space is available, minus the rotatingarea of the gearing parts, as well as the area of the shafts andbearings. This residual spatial area remaining is usable as temporarystorage.

In example embodiments, the temporary storage is in the form of areceptacle which has openings of the kind that it is able to be emptiedthrough these openings. The advantage in this case is that the temporarystorage empties when the gear unit is in the state of rest, particularlywith a first time constant. The temporary storage is filled with the aidof the delivery device in the gear unit with such a delivery rate thatthe delivered oil flow would fill the temporary storage with a secondtime constant assuming the openings were not present, this second timeconstant being smaller than the first time constant, especially morethan three times smaller or even more than ten times smaller.

In example embodiments, the temporary storage is in the form of areceptacle that has openings such that, and the delivery device isimplemented such that the maximum oil flow delivered by the deliverydevice, especially during operation of the gear unit with the nominalspeed of the gear unit, is greater than the oil flow returned from thetemporary storage to the oil pan, effected through the openings. Thisoffers the advantage that the temporary storage is able to be filledquickly, and thus the oil level of the gear unit is lowered very rapidlyafter start-up. In particular, it is advantageous to provide theopenings to be so small, and to implement the delivery device with adelivery rate, such that the oil flow delivered is at least three timesor even ten times greater than the oil flow returned.

In example embodiments, the temporary storage has an overflow,especially a height-adjustable overflow, via which excess oil is able tobe drained into the oil pan. This is advantageous in that, depending onthe variant of the gear unit, adaptation of the oil level is feasible.In addition, adaptation of the lowered oil level as a function of theoperating conditions and manufacturing tolerances is made possible.

In example embodiments, the delivery device has a baffle plate forcatching oil, oil dripping off from the baffle plate being able to befed via a drainage channel and/or collection channel to the temporarystorage. This has the advantage that a part of the delivery means isrealizable in an easy manner, and oil which is spraying around mayeasily be captured.

In example embodiments, the drainage channel or collection channel hasan opening into which a pipe opens through, from which a ball bearingand/or a gearing may be lubricated. The advantage in this case is thatthe delivery devices are inexpensive and uncomplicated.

In example embodiments, the drainage channel is curved, so that a firstportion of the oil dripped off from the baffle plate and caught by thedrainage channel flows into a first collection channel, and a secondportion of the oil dripped off from the baffle plate and caught by thedrainage channel flows into a second collection channel, the temporarystorage being fillable from the collection channels, and the collectionchannels being disposed axially to the side of a gear wheel of the gearunit. The advantage here is that the remaining spatial area, which doesnot count as part of the rotational area of the gearing parts and isprovided in the interior of the cuboidal gear unit, is usable.

In example embodiments, at least one partial area of a gearing part ofthe gear unit is surrounded by a shell, so that oil is only allowed tospray upward; in particular, the shell has an opening at its lower side,thus permitting the shell to be filled from the oil pan, especially whenthe gear unit is not in operation. The advantage in this context is thatmore oil is sprayed upward, and thus improved heat dissipation isachievable, since the oil must cover a long distance to the oil pan, theoil being in contact with the housing of the gear unit during the flowback.

In example embodiments, the delivery device includes an oil scraper thatpermits oil to be scraped off from the end face of a rotating gearwheel, and allows the scraped-off oil to be delivered through a pipe tothe temporary storage or to a collection channel, the pipe especiallybeing directed upwards, the gear wheel in particular being disposed sothat it is at least partially submerged in the oil pan, and the oilscraper in particular being situated above the oil pan. This isadvantageous in that a further inexpensive and uncomplicated deliverydevice is able to be provided. In particular, a conveying effect isattainable in order to convey oil through the pipe into a collectiondevice or a temporary storage, from which, in turn, a pipe leading intothe surroundings is able to be fed. Therefore, oil is thus able to beconveyed into the surroundings and cooled there in the cooling airflowstreaming past, especially with the aid of the plate cooler situatedthere.

In example embodiments, the pipe includes bores in the gear housing.This is advantageous because oil is able to be conveyed through thesebores toward the bearings, e.g., ball bearings. Lubrication of thesebearings may therefore be ensured.

In example embodiments, a delivery device conveys oil from the interiorof the gear unit through a pipe which is attached to the outside of thegear unit, in particular, the pipe returning the oil to the interior ofthe gear unit. The advantage in this case is that after being broughtout, the oil is able to be cooled in the outer area around the gearunit, especially in a cooling airflow which is propelled by a fanimpeller.

In example embodiments, the pipe on the outside of the gear unit has agradient, in particular, the oil from a collection device such as atemporary storage or collection channel disposed in the interior of thegear unit flowing outward through the pipe, and from there back againinto the oil pan,

in particular, the collection device being situated above the oil pan.This offers the advantage that the oil flow is able to be impelledmerely by the gradient in the gravitational field, thus, passively. Inthis context, an energy loss of the gear unit is utilized for raisingthe oil, for during operation of the gear unit, the oil in its interioris sprayed around, especially upward, as well. A portion of the oilcaught there is then conveyed downwards without a further pump,utilizing the gradient, and at the same time, is cooled.

In example embodiments, the pipe provided on the outside feeds oil to aplate cooler, and another part of the pipe returns oil from the platecooler to the oil pan in the interior of the gear unit. The advantage inthis instance is that oil is conveyed inexpensively using simple means.

In example embodiments, the plate cooler is fastened to the outside ofthe gear unit and is situated in the cooling airflow. In this case, itis advantageous that an enlarged surface is provided and improved heatdissipation is therefore attainable. In particular, the plate cooler isalignable parallel to the cooling airflow, so that the flow exhibits theleast possible turbulence.

In example embodiments, the gear unit has an input shaft,

a bearing for supporting the input shaft being provided in a housingpart of the gear unit,

a fan impeller being provided on the input shaft,

the housing part being beveled at least in the surface area adjacent tothe fan impeller and/or a beveled cowl being mounted on the housingpart.

This offers the advantage that the cooling airflow is able to be guidedas well as possible, and therefore the greatest possible portion of theairflow streams along the housing. In this manner, a powerful coolingairflow for cooling the gear unit is able to be generated by thepassively driven fan impeller, thus, driven without separate motoractuator, and great power is able to be generated per unit volume.

In example embodiments, cooling fins are provided on the beveled area ofthe housing part or on the cowl. This has the advantage that the surfaceis enlarged, thus ensuring improved heat dissipation. In particular, theheat is able to be conducted by air from the housing to the cowl, andfrom there to the surroundings. Moreover, the beveled housing part orthe beveled cowl acts as an air-guide element and reduces turbulence.

In example embodiments, cooling fins and/or cooling fingers are providedon the housing part of the gear unit. This is advantageous because thesurface is enlarged. In the case of the cooling fingers, an isotropicheat dissipation is even achievable, thus, heat dissipation independentof the installed orientation of the gear unit.

In example embodiments, a housing cover, imperviously connectable to ahousing part and having cooling fins on its outer side, is provided onthe housing of the gear unit. The advantage here is that a large openingis provided in the housing of the gear unit for assembly, maintenance orfor oil change.

In example embodiments, the cooling fins are aligned corresponding tothe direction of the cooling airflow, in particular, the cooling finsbeing aligned in parallel relative to each other. This is advantageousin that the airflow is able to be developed in a suitable manner, inparticular, an air-guide function is feasible.

In example embodiments, the input gear stage is a right-angle gearstage. This offers the advantage that a beveled housing is able to beprovided, and therefore an improved air-guide function is achievable.

In example embodiments, an air-guide containment is provided around thegear unit. This is advantageous because the cooling airflow is able tobe passed through between the gear housing and the containment, and thusvery good utilization of the cooling airflow is attainable in an easymanner. In addition, further protection is attained for the gearhousing, especially for bearing covers, screw plugs and/or oil drainplugs and the like. Such parts are therefore also practicable in plasticinstead of steel or cast steel, since the containment may be realizedfrom sheet steel, and thus a metallic protection is provided against thesurroundings.

In example embodiments, the air-guide containment guides the coolingairflow and, together with the cooling fins and the housing of the gearunit, restricts it to the spatial area provided for the cooling airflow,so that in particular, the cooling airflow absorbs as much of the heatoutput of the gear unit as possible. Of advantage here is that theairflow is able to be guided such that the best possible cooling of thehousing is attainable with the aid of the airflow.

In example embodiments, the air-guide containment has passages for theinput and output shafts, as well as for the floor mounting of the gearunit, in particular, the air-guide containment moreover having anopening for a sensor. This is advantageous in that the openings areeasily realizable, thus, do not have to be sealed off.

In example embodiments, a pipe is provided for conducting oil out of thegear-unit interior into the area of the cooling airflow, and a pipe forreturning the oil to the gear-unit interior is likewise provided in thearea of the cooling airflow, in particular, the pipes being disposedcompletely or at least partially in the cooling airflow generated by thefan impeller. The advantage in this case is that the oil of the gearunit may be cooled in an easy manner. In particular, the oil only has tobe conducted out and in again in a pipe.

In example embodiments, the oil conveyed by the pipe for conducting oilout is fed to a plate cooler situated on the housing of the gear unit,especially in the cooling airflow, in particular, the pipe for returningthe oil conveying oil from the plate cooler back into the interior ofthe gear unit. The advantage in this case is that improved heatdissipation is achievable; in particular, the plate cooler is able to bedisposed in the cooling airflow and therefore is able to be cooledpassively. The oil flow is in contact with the plate cooler for a verylong time via a meander-shaped guideway formed in the plate cooler, andis therefore able to emit the greatest possible heat flow to the air.

In example embodiments, the spatial area of a shaft bearing disposed inan opening of the gear housing is bounded at least partially withrespect to the interior of the gear unit by a delimiting device that hasan opening for a shaft supported in the bearing,

the lowest point of the opening resulting in a minimum oil level in thespatial area of the bearing. The advantage is thus that in operation, aminimum oil level is ensured in the area of the bearings, and thereforethey are well-lubricated. An oil level higher than this minimum oillevel is allowed when the gear unit is in the state of rest, and islowered during operation of the gear unit. The initial lubrication ofthe bearing is therefore very good, and nevertheless, losses duringoperation are able to be reduced.

In example embodiments, the spatial area is bounded at least partiallyby the gear housing. This is advantageous because the spatial area isthe area of the bearing, which is to be delimited with respect to thegear interior only with the aid of the protection plate.

In example embodiments, the delimiting device is a protection plate or aring. The advantage here is that an inexpensive and uncomplicateddelimitation of the spatial area is attainable.

In example embodiments, the protection plate is welded orscrew-connected to the housing. This is advantageous because a tightconnection is able to be produced in an inexpensive and uncomplicatedmanner.

In example embodiments, the ring is provided in a groove, especially agroove going round in the circumferential direction in the housing ofthe gear unit. This offers the advantage that the minimum oil level isspecifiable in an easy manner. It may be that when using such a ring,the protection against spraying oil is not so high as when using aprotection plate, but the minimum oil level is reliably adjustable in aneasy manner.

In example embodiments, the opening encircles the through-going shaft asclosely as possible, especially with a clearance of less than 3 mm,particularly of less than 1 mm.

This is advantageous because the best possible protection against oilspraying on or oil foam is achievable.

In example embodiments, the protection plate is flat, in particular,covers the area of the opening for the bearing. This is advantageousbecause a simple sheet-metal stamping is usable, in which only theexternal contour and the openings for the passage of shafts, especiallysemicircular openings which are provided at the edge area of theprotection plate, are necessary.

In example embodiments, the housing of the gear unit includes a lowerand an upper housing part, the assembly of the gear unit beingachievable very easily and inexpensively,

a protection plate which substantially surrounds the lower half of theshaft being attached to the lower housing part,

a further protection plate which substantially surrounds the upper halfof the shaft being attached to the upper housing part. The advantage inthis case is that a ring or a protection plate is able to be insertedespecially easily. In the same manner, components such as bearings,shafts and gear wheels may be installed without difficulty, for they areeasily inserted from above into the corresponding accommodation area. Inthe case of a ring, the accommodation area is a groove running in thedirection of rotation. The protection plate, on the other hand, isinsertable from above and is then able to be pressed onto the housingwall. After that, a welded connection and/or screw connection ispossible.

In example embodiments, the bearings, especially the two bearings of theinput shaft of the gear unit, are provided in a housing part,particularly in a substantially cup-shaped housing part, the housingpart being screw-connected to a housing part of the gear unit. Thisoffers the advantage that the fitting of the input shaft into a housingpart is able to be prefabricated, thus, may be preassembled. Therefore,this unit, including the input shaft, its bearings and associated seal,are able to be stocked in the warehouse and may be installed easily andquickly. In particular, a series of gear units is also able to beproduced, which offers great variance using few parts. Namely, the gearunit is realizable as a parallel shaft gear unit if the opening providedin the gear housing for the cup-shaped housing part is occluded and theinput shaft is provided at an opening in the side wall of the gear unit.Alternatively, however, the right-angle gear stage may also be providedinstead of the occluding part. Thus, a gear unit with input right-anglegear stage or input parallel shaft gear stage may be produced from thesame basic housing.

In example embodiments, a first bearing is implemented as a bearingpair, a first interspace being formed in the axial direction between thepaired individual bearings. This has the advantage that high transverseforces are able to be absorbed, and therefore a particularly stable gearunit is able to be produced. In particular, it is possible to use a pairof individual bearings, preloaded relative to each other, between whoseouter rings an interspace is therefore produced.

In example embodiments, a second bearing in the axial direction is setapart axially from the first bearing, so that a second interspace isformed. This is advantageous because, again, high transverse forces areable to be absorbed. The greater the distance between the bearings, thehigher the absorbable transverse forces.

In example embodiments, a first bearing of the input shaft takes theform of a pair of tapered-roller bearings, especially in anX-configuration, preloaded relative to each other, and a second bearingis in the form of a self-aligning roller bearing. This offers theadvantage that an especially stable set-up, able to absorb transverseforces, may be produced.

In example embodiments, the first and/or second interspace is/areconnected by one or more bores to the interior of the gear unit,particularly for the purpose of emptying. The advantage in this instanceis that good lubrication is attainable with the gear unit at rest. Tothat end, it is advantageous to plan the oil level of the gear unit tobe suitably high in the state of rest, or the position and the gradientof the bores to be suitably low. For a gear unit in operation, a minimumoil level is again able to be maintained in the interspaces by suitabledetermination of the height of the bores and of the gradient. Inparticular, bores without gradient are advantageously usable, as well. Afurther advantage of the emptying of the interspaces is that no greatquantities of oil are present long-term on the input-side seal, andtherefore the danger of an oil leak is reducible.

In example embodiments, the first and/or second interspace is/areconnected by a gap to the interior of the gear unit, especially for thepurpose of emptying, the gap being formed between the housing part,particularly the essentially cup-shaped housing part, and the housingpart of the gear unit. This is advantageous because a passage for oilmay be provided in an easy manner, thus permitting the interspace to beemptied without additional expenditure.

In example embodiments, a bore or one of the bores is a radial bore.This is advantageous because a simple and inexpensive bore may beprovided for the emptying process. In particular, it may be disposed inthe direction of gravity, so that especially effective emptying isachievable. However, to maintain a minimum oil level, a horizontalalignment of the bore is also advantageous.

In example embodiments, a bore or one of the bores is an axiallydirected bore. This is advantageous because emptying to the oil pansituated axially further inside is achievable with little effort.

In example embodiments, the radial bore is plugged at its outer end by astopper. The advantage in this case is that not only is a simple andinexpensive radial bore sufficient for the purpose of emptying, but anaccess is also created to the area of the bearings. Therefore, sensors,e.g., for determining rotational speed of the input shaft, transverseforce or axial force, or perhaps sensors for monitoring the functioningof the bearings, such as temperature sensors or structure-borne noisesensors, may also be disposed in the area of the bearings. Theassociated signal lines are able to be brought out without specialeffort through the radial bore and the suitably tightly closing stopper.

In example embodiments, an input shaft is sealed off by a shaft sealingring from the housing part, especially the cup-shaped housing part. Thisis advantageous, because an oil leak is preventable.

In example embodiments, the level of the placement of the bore or of thegap for emptying an interspace determines a minimum oil level for thebearings of the input shaft. This offers the advantage that a minimumoil level may be maintained in an easy and inexpensive manner.

LIST OF REFERENCE NUMERALS

-   1 Housing part-   2 Fan impeller-   3 Cooling fins-   4 Housing cover with cooling fins-   5 Cooling fins of housing cover 4-   6 Cooling fins on the beveled housing part-   7 Output shaft-   8 Beveled housing area for right-angle gear stage-   9 Cooling fins-   41 Rotating flange part, joined in rotatably fixed fashion to output    shaft 7-   42 Air-guide containment-   50 Discharge pipe-   51 Feed pipe-   52 Plate cooler-   53 Discharge pipe-   60 Feed pipe-   61 Feed pipe-   62 Discharge pipe-   70 Oil level during operation-   71 Oil level during standstill-   72 Bearing-   73 Shell for bevel wheel-   74 Shell for bevel pinion-   80 Temporary storage-   90 Lateral collection pockets-   91 Drainage hole for bearing lubrication-   92 Baffle plate-   93 Oil-conducting channel-   100 Pipe-   101 Scraper-   120 Gear wheel-   130 Roof-shaped housing cover-   131 Protection plate-   132 Overflow-   151 Housing cover-   160 Gear housing-   161 Gap-   162 Self-aligning roller bearing-   163 Gap-   164 Bore-   165 Housing part, cup-shaped-   166 Tapered-roller bearings in X-configuration, preloaded relative    to each other-   167 Flange part-   168 Shaft sealing ring-   169 Interspace area between two tapered-roller bearings-   170 Bore, radial-   171 Stopper-   172 Interspace area-   173 Bore, axial

Example embodiments of the present invention are explained in detailwith reference to the Figures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first gear unit according to an example embodiment of thepresent invention in a front view.

FIGS. 2 and 3 show the gear unit according to FIG. 1 from two differentviewing directions.

FIG. 4 shows a further gear unit of an example embodiment of the presentinvention in which, in contrast to FIGS. 1 through 3, a containment isadditionally provided.

FIG. 5 shows a further gear unit of an example embodiment of the presentinvention having plate cooler 52, which is attached to the housing ofthe gear unit.

FIG. 6 shows another gear unit of an example embodiment of the presentinvention, in which oil lines brought out from the gear interior andbrought in again are shown.

FIG. 7 shows another gear unit according to an example embodiment of thepresent invention in a lateral view, in which a lateral surface is cutinto, the level of the oil during operation and during standstill beingillustrated.

To that end, FIG. 8 also shows an oblique view in which conductingchannels 93 and a collection pocket 90 can be seen, as well.

FIG. 9 shows the gear unit belonging to FIG. 7 in a top view, thus, witha direction of view from above, that likewise is shown cut into, the cutbeing into the upper side.

FIG. 10 shows a scraper element belonging to the oil-delivery device.

FIG. 11 shows the scraper element in an oblique view.

FIG. 12 shows the scraper element in a top view.

FIG. 13 shows protection plates 132 against spraying oil.

FIG. 14 shows protection plates 132 separately, the plates being joinedto the gear housing.

FIG. 15 shows a housing cover 151 which is roof-like.

FIG. 16 shows a horizontal cross-section through the input right-anglegear stage.

FIG. 17 shows a top view into a similar section.

FIG. 18 shows the view from a different viewing direction.

DETAILED DESCRIPTION

In the exemplary embodiment according to FIGS. 1 through 3, a fanimpeller 2 is mounted in rotatably fixed manner on the input shaft.Thus, the fan impeller is operated with a suitably high rotational speedand generates a strong airflow with its fan-impeller blades when thegear unit is operated with the nominal speed. The higher the speed andthe torque, the greater the power loss, thus, the heat output to bedissipated to the surroundings, as well.

The cooling airflow generated by fan impeller 2 is guided along abeveled housing area 8. It is produced either by mounting suitablyformed sheet-metal pieces and joining them to housing part 1, oralternatively, by corresponding shaping of housing part 1, which ispossible without special additional effort particularly in the case of aright-angle gear stage to be provided as input.

In addition, cooling fins 6 are provided on beveled housing area 8, andcooling fins 3 and 9 are provided on housing part 1.

A housing cover 4 having cooling fins 5 is also provided on the housingpart for assembly and maintenance purposes.

In this manner, it is possible to take optimal advantage of the coolingairflow.

Output shaft 7 is implemented on both sides, but in other exemplaryembodiments, is also feasible on one side.

In FIG. 4, an air-guide part additionally provided on the gear unit,namely, an air-guide containment 42 is provided. In so doing, a passagefor the input shaft and output shaft 7 is provided. In further contrastto FIGS. 1 through 3, output shaft 7 is joined in rotatably fixed mannerto a rotating flange part 41.

Air-guide containment 42 reduces the drift of the cooling airflow, andtherefore leads to more efficient heat dissipation. It also serves asprotection against dust deposits on the gear housing, and thereforeprotects the heat-transfer resistance from the gear housing to thecooling airflow against deterioration.

In addition, further parts or components to be cooled may be disposedbetween the gear housing and the air-guide containment, such as powerelectronics or cooling devices for cooling oil. The following figuresdescribe exemplary variants for the latter.

In FIG. 5, attached to housing 1 of the gear unit is a plate cooler 52,to which oil is fed from the gear interior via one or more feed pipes50, and is carried away via one or more discharge pipes 51. Preferably,the plate cooler includes a base plate having a groove recessed in ameander form, a cover plate being mounted on the base plate. Thus, theoil must flow through the plate cooler in meandering fashion.Alternatively, straight bores may also be arranged in a base element andthe oil conducted through the bores, deflection pieces being providedbetween the end areas of the bores on the base element.

On the rear side with respect to the side of the gear unit having theplate cooler, thus the side not visible in FIG. 5, a plate cooler 52having the corresponding pipes may likewise be provided, so that adoubling of the cooling capacity is attainable.

Plate cooler 52 is omitted in FIG. 6. Feed pipes 60 and 61 are broughttogether and lead into discharge pipe 62. Thus, the pipes are exposeddirectly to the cooling airflow, and particularly if oil flows throughthem slowly, sufficient cooling capacity may be attained, even withoutthe expenditure of a cooling plate.

FIG. 7 shows that level 70 of the oil during operation is loweredcompared to level 71 of the oil during standstill. Therefore, uponstart-up of the gear unit, good lubrication is available immediately forall bearings, especially the bearings of the input gear stage orbearings 72 of one or more of the intermediate stages of the gear unitas well, since the oil level is so high that the bearings and gearingparts are situated sufficiently deep in the oil pan. Thus, goodlubrication is present, even when the gear unit is started after longstandstill times.

The input stage of the gear unit is arranged as a right-angle gearstage. To that end, provided on the input shaft is a bevel pinion whichmeshes with a bevel wheel. Churning losses are reduced by a shell 73 forthe bevel wheel and a shell 74 for the bevel pinion, which in each caseare provided about the lower half of these gearing wheels, for shells(73, 74) are formed such that at least in the area of shells (73, 74),the oil is substantially kept on a circular path during rotationalmovement of the gearing parts. Therefore, the inner area between therespective shell and gearing part is thus freed of oil, or at least theportion of oil is reduced substantially in this area.

Since shells (73, 74) basically surround only the lower half of thegearing parts, oil is only sprayed upwards. Therefore, during theflow-off impelled by gravity, the oil must cover long distances alongthe inner surface of the housing and/or along a delivery arrangement,which means good heat dissipation from the oil to the gear housing isattainable. At their lower side, shells (73, 74) have at least oneopening, so that oil from the oil pan is able to flow back into thespatial area between shell (73, 74) and the gearing part. However, theopening is so small that the oil flow into the spatial area is at leastfive times or at least ten times less than the oil flow which thegearing part is able to convey out of the spatial area when the nominalspeed of the input shaft is reached during operation.

Shells (73, 74) are preferably in the shape of a half torus.

As FIG. 8 shows more clearly, with the aid of the oil-deliveryarrangement described in greater detail below, during operation, oil isconveyed into a higher-situated temporary storage 80, so that the oillevel drops. Because of this lowering of the oil level during operation,it is possible to reduce the churning losses. That is to say, thegearing parts engage only slightly within the oil pan, in particular,the rapidly rotating gearing parts, such as the gearing parts of theinput gear stage and one or more intermediate gear stages, dip lessdeeply or not at all into the oil pan.

Temporary storage 80 has leakages or small openings otherwise provided,so that the temporary storage is emptied automatically. The openings areprovided such that the intended lowering of the oil level takes placeduring operation at nominal value, thus, the oil flow which streams intotemporary storage 80 is greater than the oil flow which flows back fromtemporary storage 80 into the oil pan—at least so long as the oil levelin the temporary storage is below a critical value.

Therefore, in operation, the temporary storage is thus filled with theaid of the oil-delivery arrangement, and consequently, with rising oillevel in temporary storage 80, the oil level in the gear unit islowered, especially in the oil pan, so that the power losses arereduced.

During operation, the bearings and gearings are lubricated in a mannerthat the oil squeezed out of the engaging gearings and/or sprayed iscaught with the aid of baffle plates 92 and drips off from them intooil-conducting channels 93 that fill lateral collection pockets 90, fromwhich at least a portion of the oil caught is supplied to the bearingsto be lubricated and the gearing parts to be lubricated.

As FIG. 9 shows, to that end, collection pockets 90, situated on bothsides in the gear unit, have drainage holes 91 for the bearinglubrication. The drainage holes discharge into bores in the housing,through which the oil is conducted to the bearing to be lubricated orvia conducting channels to the respective gearing part to be lubricated.

Oil-conducting channels 93 are curved, so that a portion of the caughtoil is conducted into a first, and another portion is conducted into theother collection pocket 90.

Lubrication of the gearing parts and the bearings of the output shaft isnot always necessary, since these gearing parts rotate slowly andconsequently produce only negligible churning losses. Therefore, dippingof these gearing parts and bearings into the oil pan is not harmful.

Preferably, baffle plates 92 and oil-conducting channels 93 are attachedto the upper side of the gear housing.

The drainage holes are positioned in collection pockets 90 in such away, and the collection pockets are implemented such that the oilarriving first upon starting the gear unit is used to lubricate thebearings or gearing parts. Only when the caught oil flow exceeds thisoil flow necessary for the lubrication is temporary storage 80 filled.

In a further exemplary embodiment, temporary storage 80 preferably hasan adjustable overflow. To that end, an opening, envisaged in thehorizontal direction, may be provided in a side wall of temporarystorage 80 and may be covered by a sheet-metal cover part disposed in amanner allowing it to slide in the horizontal direction. The overflowlevel, and thus also the maximum volume of temporary storage 80, istherefore adjustable by the sliding of the sheet-metal cover part.

FIG. 10 illustrates a further oil-delivery device that shows a scraper101 which scrapes off oil at an end face of a gear wheel and pushes itinto pipe 100, from which lateral collection pockets 90 are able to befilled, as well. The previously described oil-delivery device, includingoil-conducting channels 93, is additionally effective. In this manner,oil moving along on the gear wheel and sprayed around by the gear wheelis thus able to be caught and used to lubricate bearings or to lower theoil level in operation.

Scraper 101 together with pipe 100 are shown separately in FIG. 11.Here, it is more apparent that the scraper has a V-shaped recess, atwhose pointed end, a borehole is provided, into which pipe 100 leads.

FIG. 12 shows the placement of scraper 101 on gear wheel 120.

FIG. 13 shows another gear unit in which, in contrast to the figuresdescribed above, instead of housing cover 4, a housing cover 130 isprovided that is roof-shaped. Therefore, oil dripping off from the innerside of this roof-shaped housing cover is able to be led away byoil-conducting channels 93 into collection pockets 90. Thus, in thismanner, it is not oil flung in the horizontal direction as in the caseof the baffle plate, but rather oil flung in the vertical directionagainst the inner side of roof-shaped housing part 130 that is able tobe caught and utilized.

FIG. 15 shows a housing cover 151 which is V-shaped, thus roof-shaped,the tip of the V pointing upward. In this case, the angle of the roofarea, thus, the angle of the respective side of the V with respect tothe horizontal is greater than 10°. Preferably, the angle is selected sothat the drops sprayed onto the inside of the roof-shaped housing covermove downward laterally on the roof slope under the influence ofgravity, in the course of which, they are bound adhesively to the roof,and then drip off into oil-conducting channels 93. The angle is thusalways selected so that the gravitational force is less than theadhesive force for drops sticking adhesively to the surface. In thiscontext, the angle is also essentially a function of the surface tensionbetween oil and housing cover 151.

FIG. 13 also shows protection plate 131, which is used to protect ballbearings from oil sprayed around or from oil foam driven in thedirection of ball bearings. Protection plate 131 is sufficiently widethat even several ball bearings are protectable, especially the ballbearing of the input shaft, of an intermediate shaft and/or of outputshaft 7. Protection plate 131 is secured to the inner side of thehousing, and is implemented with openings so large that the rotationallymounted parts belonging correspondingly to the respective ball bearingsno contact with protection plate 131.

In FIG. 13, a distance sleeve is mounted between the gear wheel and theassociated ball bearing on the shaft to maintain a defined distancebetween the ball bearing and gear wheel. Thus, the distance sleeve isprovided in an opening in protection plate 131.

Protection plate 131 has an overflow 132, so that oil from the oil panarrives in the area of the protected ball bearings when the oil level ofthe oil pan is higher than the overflow, thus, especially the overflowedge.

Protection plate 131 is welded or screw-fitted to the inner side of thehousing, so that the ball bearings are in oil. Especially also inoperation, thus, when the oil level in the oil pan falls, there is stilla minimum oil level around the ball bearing. In this case, it is alsofurther advantageous that the oil supplied to the gearing parts with theaid of the delivery device accumulates in the spatial area around theball bearing, which is at least partially bounded by protection plate131; a flow-off of the oil is also provided when the minimum oil levelaround the ball bearing exceeds overflow 132.

The implementation having protection plate 131 is shown in greaterdetail in FIG. 14. A lower and an upper protection plate 131 are used,the housing of the gear unit likewise being split into a lower and anupper housing part. Lower protection plate 131 is secured, especiallyscrew-fitted, to the lower housing part, and upper protection plate 131to the upper housing part, as shown in FIG. 14, or welded on, as in analternative exemplary embodiment.

In an alternative exemplary embodiment, instead of protection plate 131,a ring inserted in a groove is provided, which therefore defines anoverflow with the aid of the lowest encompassed point. The ring, then,is not able to represent a substantial splash protection, but is able torealize the function of the overflow.

In a further exemplary embodiment, an aforementioned protection plate isused in the case of a first bearing, and the aforementioned ring is usedin the case of another bearing.

In the exemplary embodiment according to FIGS. 16, 17 and 18, the inputright-angle gear stage is shown in greater detail. It is implemented asa bevel-gear stage.

A cup-shaped housing part 165 is screw-fitted to gear housing 160 at theaxial end, to which, in turn, a flange part 167 is screw-fitted, thataccommodates a shaft sealing ring 168 which seals off the gear interiorfrom the outer surroundings.

In cup-shaped housing part 165, two tapered-roller bearings 166,preloaded relative to each other, are provided in X-configuration, whoseaxial distancing from each other creates an interspace area 169. Thisinterspace area 169 is thus bounded by the two tapered-roller bearings166 and cup-shape housing part 165.

When the gear unit is not in operation, and therefore at high oil level,interspace area 169 is at least partially filled with oil, since itflows into it from the interior of the gear unit. During operation, theoil level of the oil pan in the gear unit is lowered. Interspace area169 is emptied via a radial bore 170 which leads into interspace 169 andwhich is closed at its outer radial end by a stopper 171. An axial bore173 leads from radial bore 170 back into the interior of the gear unit.The positioning of the bores, especially the height provided relative tothe oil pan, makes it possible to maintain a defined minimum oil levelin interspace area 169. The emptying of interspace area 169, except forthis minimum oil level, leads to a decrease in losses, since thebearings are then less surrounded by the oil.

A further interspace area 172 between tapered roller bearing 166,situated axially further inside, and self-aligning roller bearing 162,via which the input shaft is supported in cup-shaped housing part 165,is emptied in analogous manner. For that purpose, radial bore 164 isprovided, which opens through into an axially inwardly leading gap 163that is situated between housing 160 of the gear unit and cup-shapedhousing part 165, and widens axially further inwardly into a gap 161.

At its end area situated axially inside, the input shaft bears the bevelpinion, which meshes with a bevel wheel that is supported by bearingsprovided in housing 160 of the gear unit.

What is claimed is:
 1. A gear unit at least partially filled with oil,comprising: a device arranged in the gear unit and adapted to lower anoil level of an oil pan of the gear unit during operation, the deviceincluding at least one temporary storage, wherein an air-guidecontainment is provided around the gear unit.
 2. The gear unit accordingto claim 1, wherein the oil level in the temporary storage is higherduring operation of the gear unit than the oil level of the oil pan ofthe gear unit.
 3. The gear unit according to claim 1, wherein thetemporary storage is arranged in an interior of the gear unit.
 4. Thegear unit according to claim 1, wherein the temporary storage is in theform of a receptacle having a wall formed at least partially by at leastone of (a) a sheet-metal piece and (b) a plastic piece, at leastpartially together with an inner wall of a housing of the gear unit. 5.The gear unit according to claim 1, wherein the oil level of the oil panof the gear unit is lower during operation lasting for a minimumduration than the oil level during a long-term standstill of the gearunit.
 6. The gear unit according to claim 1, wherein oil is deliverablefrom the oil pan of the gear unit to the temporary storage, with the aidof a delivery device, the temporary storage being disposed in aninterior of the gear unit, being surrounded by a gear housing inhousing-forming fashion.
 7. The gear unit according to claim 1, whereinthe temporary storage is arranged as a receptacle having emptyingopenings.
 8. The gear unit according to claim 1, wherein the temporarystorage is in the form of a receptacle that has openings, the gear unitfurther comprising a delivery device arranged such that a maximum oilflow delivered by the delivery device, during operation of the gear unitwith a nominal speed of the gear unit, is greater than an oil flowreturned from the temporary storage to the oil pan, effected through theopenings.
 9. The gear unit according to claim 1, wherein the temporarystorage includes at least one of (a) an overflow and (b) aheight-adjustable overflow, via which excess oil is drainable into theoil pan.
 10. The gear unit according to claim 1, wherein a deliverydevice includes a baffle plate, provided on an inner wall of an upperside of the gear unit, adapted to catch oil, oil dripping off from thebaffle plate being feedable via at least one of (a) a drainage channeland (b) a collection channel to the temporary storage.
 11. The gear unitaccording to claim 10, wherein at least one of (a) the drainage channeland (b) the collection channel includes an opening into which a pipeopens through, with whose aid at least one of (a) a ball bearing and (b)a gearing is lubricatable.
 12. The gear unit according to claim 10,wherein the drainage channel is curved, so that a first portion of oildripped off from the baffle plate and caught by the drainage channelflows into a first collection channel, and a second portion of oildripped off from the baffle plate and caught by the drainage channelflows into a second collection channel, the temporary storage beingfillable from the collection channels, and the collection channels beingdisposed axially to a side of a gear wheel of the gear unit, extendingin an axial direction of the gear wheel.
 13. The gear unit according toclaim 1, wherein at least one partial area of a gearing part of the gearunit is surrounded by a shell, enveloping the partial area of thegearing part, such that oil is sprayed upwardly, up to an upper side ofan interior of the gear unit, oil only being permitted to spray upward,the shell having an opening at a lower side, permitting the shell to befilled from the oil pan, when the gear unit is not in operation.
 14. Thegear unit according to claim 1, wherein a delivery device is adapted toconvey oil from an interior of the gear unit through a pipe which isattached to an outside of the gear unit, the pipe adapted to return oilto the interior of the gear unit.
 15. The gear unit according to claim1, wherein a pipe on an outside of the gear unit has a gradient, the oilfrom at least one of (a) a collection device, (b) the temporary storage,and (c) a collection channel disposed in an interior of the gear unitflowing outwardly through the pipe, and from there back again into theoil pan, the collection device being situated above the oil pan.
 16. Thegear unit according to claim 1, wherein the gear unit includes an inputshaft, a bearing adapted to support the input shaft arranged provided ina housing part of the gear unit, and a fan impeller arranged on theinput shaft, at least one of (a) the housing part being beveled at leastin a surface area adjacent to the fan impeller and (b) a beveled cowlbeing mounted on the housing part.
 17. The gear unit according to claim16, wherein cooling fins are provided on at least one of (a) the beveledarea of the housing part and (b) the cowl.
 18. The gear unit accordingto claim 17, wherein the cooling fins are aligned corresponding to adirection of cooling airflow and are aligned in parallel relative toeach other.
 19. The gear unit according to claim 16, wherein coolingfins are provided on the housing part of the gear unit.
 20. The gearunit according to claim 1, wherein the air-guide containment is adaptedto guide a cooling airflow and, together with cooling fins and a housingof the gear unit, is adapted to restrict, so that the cooling airflowabsorbs as much of the heat output from the gear unit as possible. 21.The gear unit according to claim 1, wherein the air-guide containmentincludes passages for an input shaft and an output shafts as well as fora floor mounting of the gear unit, the air-guide containment includingan opening for a sensor.
 22. The gear unit according to claim 1, whereina pipe is provided for conducting oil out of the gear-unit interior intoan area of a cooling airflow, and a pipe is provided for returning theoil to the gear-unit interior, the pipes being arranged at leastpartially in the cooling airflow generated by a fan impeller.
 23. Thegear unit according to claim 22 , wherein a part of the pipe brought outof an interior of the gear unit is arranged between a gear housing andan air-guide containment.
 24. The gear unit according to claim 1,wherein a spatial area of a shaft bearing disposed in an opening of agear housing is bounded at least partially with respect to an interiorof the gear unit by a delimiting device that has an opening for a shaftsupported in the bearing, a lowest point of the opening resulting in aminimum oil level in the spatial area of the bearing.
 25. The gear unitaccording to claim 24, wherein the spatial area is bounded at leastpartially by the gear housing.
 26. The gear unit according to claim 24,wherein the delimiting device includes at least one of (a) a protectionplate and (b) a ring.
 27. The gear unit according to claim 26, whereinthe protection plate is at least one of (a) welded and (b)screw-connected to the housing.
 28. The gear unit according to claim 26,wherein the ring is provided in a groove extending around in acircumferential direction in the housing of the gear unit.
 29. The gearunit according to claim 26, wherein the protection plate is flat, andcovers an area of an opening for a bearing.
 30. The gear unit accordingto claim 1, wherein an opening encircles a through-going shaft asclosely as possible, with a clearance of at least one of (a) less than 3mm and (b) less than 1 mm.
 31. The gear unit according to claim 1,wherein a housing of the gear unit includes a lower and an upper housingpart, a protection plate which substantially surrounds a lower half of ashaft being attached to the lower housing part, a further protectionplate which substantially surrounds an upper half of the shaft beingattached to the upper housing part.
 32. The gear unit according to claim1, wherein two bearings of an input shaft of the gear unit are providedin a substantially cup-shaped housing part, the housing part beingscrew-connected to a housing part of the gear unit.
 33. The gear unitaccording to claim 32, wherein a first bearing is arranged as a bearingpair, a first interspace being formed in an axial direction between thepaired individual bearings.
 34. The gear unit according to claim 33,wherein a second bearing in the axial direction is set apart axiallyfrom the first bearing, so that a second interspace is formed.
 35. Thegear unit according to claim 34, wherein at least one of (a) the firstinterspace and (b) the second interspace is connected by at least onebore to an interior of the gear unit, for the purpose of emptying. 36.The gear unit according to claim 35, wherein at least one bore isarranged as a radial bore.
 37. The gear unit according to claim 36,wherein the radial bore is plugged at an outer end by a stopper.
 38. Thegear unit according to claim 35, wherein at least one bore is arrangedas an axially directed bore.
 39. The gear unit according to claim 35,wherein a level of placement of the bore for emptying an interspacedetermines a minimum oil level for bearings of an input shaft.
 40. Thegear unit according to claim 34, wherein at least one of (a) the firstinterspace and (b) the second interspace is connected by a gap to aninterior of the gear unit, for the purpose of emptying, the gap beingformed between a substantially cup-shaped housing part and a housingpart of the gear unit.
 41. The gear unit according to claim 1, wherein afirst bearing of an input shaft takes the form of a pair oftapered-roller bearings, in an X-configuration, preloaded relative toeach other, and a second bearing is in the form of a self-aligningroller bearing.
 42. The gear unit according to claim 1, wherein an inputshaft is sealed off by a shaft sealing ring from a cup-shaped housingpart.
 43. A gear unit at least partially filled with oil, comprising: adevice arranged in the gear unit and adapted to lower an oil level of anoil pan of the gear unit during operation, the device including at leastone temporary storage, wherein a housing cover which is tightlyconnectable to a housing part and which has cooling fins on its outerside is provided on a housing of the gear unit.
 44. A gear unit at leastpartially filled with oil, comprising: a device arranged in the gearunit and adapted to lower an oil level of an oil pan of the gear unitduring operation, the device including at least one temporary storage,wherein an input gear stage includes a right-angle gear stage.